More answers

anonymous

2 years ago

i will walk you through it

anonymous

2 years ago

we need two numbers, the amount invested at 7% and the amount invested at 6%
to do a problem like this, you need to have a variable representing some number you want,
then you need an equation to solve
but the first step is to make a variable
you pick it

anonymous

2 years ago

pick some letter to represent the amount invested at 7% interest

anonymous

2 years ago

you can pick such your smart and you know what your doing

anonymous

2 years ago

there are 26 letters in the alphabet, you do not need to be smart to pick one of them

anonymous

2 years ago

just asking are you a boy or girl?

anonymous

2 years ago

also there is the greek alphabet, you can pick a letter from there too
the indians used colors for there variables

misty1212

2 years ago

HI!!

misty1212

2 years ago

why don't you pick \(x\) that is what the math teachers usually use

anonymous

2 years ago

ok \(x\) it is
then if the amount invested at 7% is \(x\) and the total is \(20,000\) then the amount invested at 6% is \(20,000-x\)

anonymous

2 years ago

then

misty1212

2 years ago

7% of \(x\) is \(0.07x\) right?
at 6% of \(20,,000-x\) is \(.06(20,000-x)\)

anonymous

2 years ago

yes, and since the total interest is 1280 you know that
\[.07x+.06(20,000-x)=1280\]

anonymous

2 years ago

final job is to solve that for \(x\)

misty1212

2 years ago

yeah but decimals are so annoying

anonymous

2 years ago

k lets get rid of them by multiplying both sides by 100 to clear the decimals

misty1212

2 years ago

oh ok, then we can just solve
\[7x+6(20,000-x)=128,000\]

anonymous

2 years ago

yeah if you multiply both sides by 100 the decimal goes, and of course you have to multiply \(1280\times 100\) to get \(128,000\)

misty1212

2 years ago

now it should be easy right? distribute the 6
then combine like terms
then you can solve for \(x\) in one step

anonymous

2 years ago

so x is suppose to equal to?

misty1212

2 years ago

you still have to find \(x\) by solving \[7x+6(20,000-x)=128,000\]

anonymous

2 years ago

i mean how much does he invest at each rate?

misty1212

2 years ago

solve for \(x\) and you will know how much is invested at 7%
do you know how to do that?

anonymous

2 years ago

no

anonymous

2 years ago

its all too confusing

misty1212

2 years ago

then skip it
you need to know how to solve basic linear equations first before you can worry about complicated word problems

anonymous

2 years ago

but its homework and i need to finish it,its due tomorrow that's why i need help to find what x is

terenzreignz

2 years ago

Well, let's see what we can do ^^
Do you know what "distribute" means in this context?
\[7x+\color{red}6(\color{blue}{20,000}-\color{green}x)=128,000\]

misty1212

2 years ago

it is too confusing
go back and learn how to solve linear equations first
then you need to know how to set up a word problem
finally you can tackle something like this
there is not royal road to algebra, you have to do it step by step

terenzreignz

2 years ago

Miss Tea scared her off D:
Oh noes

misty1212

2 years ago

any one who starts of with "i don't get it" "this is too confusing" "this doesn't make sense" is not ready to begin a problem like this
you could go ahead and give the answer, but it will make no sense at all
look at all the work we did just to set up the equation
need to go back and learn the basics, then we can tackle something like this

terenzreignz

2 years ago

Aww, there's no need to get so extreme ^^
Come on, @vickie11223
work with me here. What I want you to do is distribute the 6 to the two terms inside the parentheses.
What that means is you multiply 6 to those two terms.
Can you do that?
\[7x+\boxed{6(20,000-x)}=128,000\]
Focus on the stuff in the box first.

anonymous

2 years ago

yes

terenzreignz

2 years ago

|dw:1439057511466:dw|

terenzreignz

2 years ago

My handwriting is terrible, but this might give you a better idea on what "distribution" is.
Multiply ^^

anonymous

2 years ago

120000-6x

terenzreignz

2 years ago

Great.
So going back to the equation, we get
\[\Large 7x+ \color{blue}{120000 - 6x}=128,000\]
Anything you can simplify?

anonymous

2 years ago

minus 120,000 to 128000

terenzreignz

2 years ago

Not the more obvious thing to do, but sure. Just so we're clear, what will your equation look like after that?

anonymous

2 years ago

or minus 7x to negtive 6x

terenzreignz

2 years ago

Slowly, now ^^
Step by step.
Show your steps. All of them. Preferably one at a time. I'll add my commentary to them XD

anonymous

2 years ago

i don't know would you like to show me?

terenzreignz

2 years ago

I would love to, but you know, you already outlined two things that you CAN do.
I wanted you to show me your steps so I can make sure you're doing them correctly :D

anonymous

2 years ago

um 7x+8000-6x?

anonymous

2 years ago

ugh im so stupid

terenzreignz

2 years ago

Okay. This could use some work XD
Remember that we're dealing with equations here, you need to have the = sign.
And never ever admit to stupidity haha

anonymous

2 years ago

7+-6x+=8000

terenzreignz

2 years ago

I'd rather you showed me your steps.
But... anyway, can I trust that you knew what you were doing when you got to this equation?

terenzreignz

2 years ago

oh and uhh
you missed a spot.
x's don't just disappear ;)
HAHA no pun intended

anonymous

2 years ago

|dw:1439058198385:dw|

anonymous

2 years ago

is this right

terenzreignz

2 years ago

As a matter of fact, yes ^^
Now you got x.
That's the amount invested for 7% as I recall
What about the amount invested for 6%?

anonymous

2 years ago

can you show me the equation?

terenzreignz

2 years ago

no need for that, just simple logic.
The bloke invested 20,000, yes?
one part for 7% which is 8000
the rest has to have been invested for 6%
Take 8000 from 20000, what do you have left? ^_^

anonymous

2 years ago

12000

terenzreignz

2 years ago

and there you go ^^

terenzreignz

2 years ago

Just to make sure, what's 6% of 12000?

anonymous

2 years ago

idk would youlike to help me lol

terenzreignz

2 years ago

Come on -_-
Calculators can do that for you. haha

anonymous

2 years ago

hahaha i dont have one with me do you

terenzreignz

2 years ago

okay, to get 6% of something, multiply it by 0.06
Now, what's 6% of 12000?

anonymous

2 years ago

720

terenzreignz

2 years ago

Right.
What's 7% of 8000?
Multiply by 0.07
;)

anonymous

2 years ago

but i need to find how much does he invest at each rate

terenzreignz

2 years ago

Didn't you already do that?
You defined x as the amount he invested for 7% and you got... what?

terenzreignz

2 years ago

What is x?

anonymous

2 years ago

560

terenzreignz

2 years ago

That's 7% of 8000 lol

anonymous

2 years ago

8000?

terenzreignz

2 years ago

now add them up. 560 and 720 and you get?

anonymous

2 years ago

1220

terenzreignz

2 years ago

I don't think so?

anonymous

2 years ago

1280

terenzreignz

2 years ago

And that's exactly how much interest he was supposed to earn, as per your problem.
Good job!

anonymous

2 years ago

but thats how much he yielded

anonymous

2 years ago

i need to find how much he invest at each rate

terenzreignz

2 years ago

I know. That was only supposed to check that your answer was correct, and it is ^^
x is how much he invested at 7% and you already got a value for x.

anonymous

2 years ago

which is 1280

anonymous

2 years ago

that is what i put as my answer

terenzreignz

2 years ago

no.
Look back to the equation you solved. You got a value for x.

anonymous

2 years ago

8000

terenzreignz

2 years ago

That's right.

anonymous

2 years ago

and that is the value of x

terenzreignz

2 years ago

and that's how much he invested at 7%

anonymous

2 years ago

oh thank you your so smart

anonymous

2 years ago

i need help with one more question

terenzreignz

2 years ago

Just a little ;)
Now that this is done, do in fact, follow Misty's lead and give your "solving linear equations" a thorough review.

anonymous

2 years ago

;)

anonymous

2 years ago

i think i need a one on one tutor like you

terenzreignz

2 years ago

There are plenty of those. Here.
They'll only be too happy to help you...sometimes all at once haha